Nyedra W. Booker, PharmD, MPH
Is your child playing on rubber instead of grass at the playground? The use of human-made surfaces on playgrounds has increased dramatically over the years. Developed during the 1960s primarily for athletic fields, these artificial surfaces were also part of a strategy to provide children with more opportunities for outdoor physical activity, particularly in the inner city where outdoor playgrounds were scarce. The first artificial turf (marketed as “Chemgrass”) was made of plastic, yet looked a lot like natural grass. As its use for various sports activities increased significantly over the years, so did the concerns. Athletes began to complain that the surface was much harder than natural grass, as some studies also began to show that the use of artificial turf could increase the risk for football and other sports-related injuries. This prompted a ban on the use of artificial turf by the English Football Association in 1988, while many ballparks and professional sports stadiums in the United States began converting back to using natural grass during the 1990s.  Over time, material such as rubber was added to keep the blades of “grass” in place and provide more cushioning.  Some of the benefits of artificial turf are that it’s a long-lasting “all-weather” material that does not require a lot of maintenance or potentially dangerous pesticides. Artificial turf containing rubber and other cushioning materials is also believed to reduce sports-related injuries, but study results have been mixed. Artificial turf is currently used on approximately 4,500 playgrounds, tracks and fields in the U.S. 
From Tire Swings to Play Surfaces Made from Tires
Do you remember when children use to play on tire swings in the backyard or at the park? Those same tires are now being put to a new and possibly hazardous use! Recycled rubber tires have become one of the top choice materials for surfacing children’s playgrounds. According to the U.S. Environmental Protection Agency (EPA), approximately 290 million scrap tires are generated each year, with 28 million being ground up for various surfaces. Logically, tire scraps seemed like a surface that would be less likely to harm children if they fell. Recycling tires for use in playgrounds also keeps them out of landfills where they take up space, harbor rodents and other animals, and trap standing water that serve as breeding grounds for mosquitos and other disease-bearing insects. In addition, tires that have been thrown away can catch fire and that releases many different harmful chemicals into the air and ground water.  
The tire material used on playgrounds can include the following:
- Uncompressed/loose tire shred (rubber mulch) or “crumb” on a surface that can be raked
- Tire shreds combined with a binder and then poured onto a permanent surface
- Tiles made from tire shreds and binder that have been factory-molded then glued to a playground surface4
Are Playground Surfaces Made with Recycled Tires Safe?
There has been increasing evidence that raises concerns about the safety of recycled tire material used on playground surfaces. While tire rubber includes natural rubber from rubber trees, it also contains phthalates (chemicals that affect hormones) -see Phthalates and Children’s Products), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs) and other chemicals known or suspected to cause adverse health effects. Polycyclic aromatic hydrocarbons, for example, are natural or human-made chemicals that are made when oil, gas, coal or garbage is burned.  According to the EPA, breathing air contaminated with PAHs may increase a person’s chance of developing cancer, and the Agency for Toxic Substances and Disease Registry (ATSDR) states that PAHs may increase the risk for cancer and also increase the chances of birth defects. 
What the Scientific Studies Say
The California Office of Environmental Health Hazard Assessment (OEHHA) conducted three laboratory studies in 2007 to investigate the potential health risks to children from playground surfaces made from recycled tires. One study evaluated the level of chemicals released that could cause harm to children after they have had contact with or ingested loose tire shreds-either by eating them or by touching them and then touching their mouth. The other two studies looked at the risk of injury from falls on playground surfaces constructed from recycled tires compared to wood chips, as well as the potential contamination of air and water due to recycled tire shreds.
The ingestion part of the study did not involve children ingesting tire shreds; instead, researchers developed a solution that mimicked the conditions of a child’s stomach and placed 10 grams of tire shreds in it for 21 hours at a temperature of 37°C. Researchers then measured the level of released chemicals in the solution and compared them to levels established by the EPA as risky. The part of the study meant to mimic a child touching the tire shreds and then touching her mouth was performed by wiping recycled tire playground surfaces and measuring chemical levels on the wipes. To look at skin contact alone, the researchers used guinea pigs and tested them to see how sensitive they were to rubber tire playground samples. This study assumed that children would be using the playground from the ages of 1 through 12. Results of the OEHHA studies showed that while a one-time ingestion of, or skin contact with tire shreds would probably not cause any health effects in children, repeated or long-term exposure might. Five chemicals, including four PAHs, were found on wipe samples. One of the PAHs-”chrysene”-exceeded minimal risk levels established by the OEHHA, and therefore, could potentially increase the risk of cancer in children. 
Out of the 32 playgrounds surfaced in recycled tires that the researchers in California looked at, only 10 met that state’s 2007 standard for “head impact safety” to reduce brain injury and other serious trauma in children who fall while playing. In contrast, all five surfaces made of wood chips met the safety standard.
A 2012 study analyzing rubber mulch taken from children’s playgrounds in Spain found harmful chemicals present in all, frequently at high levels. Twenty-one samples were collected from 9 playgrounds in urban locations and screened for various pollutants. The results showed that all samples contained at least one hazardous chemical, with most containing multiple PAHs found at high concentrations. Several of the identified PAHs can be released into the air by heat, and when that happens children are likely to inhale them. While the heat needed to do this was very high in some cases (140 degrees Fahrenheit/ 60 ºC), many of the chemicals also became airborne at a much lower temperature of 77 ºF (25 ºC). The authors concluded that the use of rubber recycled tires on playgrounds “should be restricted or even prohibited in some cases.”
What the EPA Has Done
The EPA created a working group that collected and analyzed data from playgrounds and artificial turf fields that used recycled tire material. Samples were collected at six turf fields and two playgrounds in four study sites (Maryland, North Carolina, Georgia and Ohio). In a report released in 2009, the agency concluded that the level of chemicals monitored in the study and detected in the samples were “below levels of concern.” There were limitations to this study however. Due to the small number of samples and sampling sites used, the EPA stated that “it is not possible to extend the results beyond the four study sites or to reach any more comprehensive conclusions.”
A meeting was then convened by the EPA in 2010, bringing together various state and federal agencies to discuss safe levels of chemical exposure on playgrounds made from recycled tire rubber, and opportunities for additional research. In the case of PAHs, the EPA has concluded that while there are currently no human studies available to determine their effects at various levels, based on laboratory findings, “breathing PAHs and skin contact seem to be associated with cancer in humans.” 
How to Protect Your Children?
So how can you protect your child at the playground? Remember that children are much more likely to be harmed by exposure to chemicals in their environment than adults because they are smaller (so the exposure is greater) and because their bodies are still developing. This is why it’s important to significantly reduce (or try to eliminate) any contact your child may have with substances that are known or suspected to be harmful. If you have more than one playground in your area, choose the one that doesn’t have a recycled rubber play surface.
Parents can actively persuade local officials that playgrounds should use wood chips rather than recycled rubber or other substances that are less safe when children fall, and more dangerous in terms of chemicals that they breathe or get on their hands.
The Centers for Disease Control and Prevention (CDC), Consumer Product Safety Commission (CPSC) and EPA all recommend that you teach your child the importance of frequent hand washing, especially after playing outside and before eating. Also, if you notice any loose tire shreds or other debris on your child after being at the playground, remove his/her shoes and clothing before entering the home.
 US Environmental Protection Agency (EPA). Fact Sheet-The Use of Recycled Tire Materials on Playgrounds & Artificial Turf Fields. http://www.epa.gov/nerl/download_files/documents/fs_tire_crumbs.pdf Accessed September 5, 2012.
 Claudio L. Synthetic Turf-Health Debate Takes Root. Environmental Health Perspectives, 2008; 116(3):A117-22.
 New York State Department of Health. . Fact Sheet: Crumb-Rubber Infilled Synthetic Turf Athletic Fields. August 2012 (last revised). http://www.health.ny.gov/environmental/outdoors/synthetic_turf/crumb-rubber_infilled/fact_sheet.htm Accessed September 21, 2012.
 State of California-Office of Environmental Health Hazard Assessment (OEHHA), Contractor’s Report to the Board. Evaluation of Health Effects of Recycled Waste Tires in Playground and Track Products. January 2007. http://www.calrecycle.ca.gov/publications/Documents/Tires%5C62206013.pdf Accessed September 5, 2012.
 US Environmental Protection Agency (EPA). Wastes-Resource Conversation-Common Wastes & Materials – Scrap Tires (Frequent Questions). http://www.epa.gov/osw/conserve/materials/tires/faq.htm Accessed September 5, 2012.
 Earth 911.com. Benefits of Recycling Tires. http://earth911.com/recycling/automotive/tires/benefits-of-recycling-tires/ Accessed September 5, 2012.
 Llompart M, Sanchez-Prado L, Lamas JP, Garcia-Jares C, et al. Hazardous organic chemicals in rubber recycled tire playgrounds and pavers. Chemosphere. 2012; Article In Press. http://dx.doi.org/10.1016/j.chemosphere.2012.07.053.
 US Environmental Protection Agency (EPA). Polycyclic Aromatic Hydrocarbons (PAHs)-Fact Sheet. January 2008. http://www.epa.gov/osw/hazard/wastemin/minimize/factshts/pahs.pdf Accessed September 5, 2012.
 National Institutes of Health (NIH), National Cancer Institute. Reducing Environmental Cancer Risks (What We Can Do Now), 2008-2009 Annual Report of the HHS President’s Cancer Panel. April 2010. http://deainfo.nci.nih.gov/advisory/pcp/annualreports/pcp08-09rpt/PCP_Report_08-09_508.pdf Accessed September 17, 2012.